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The point was made earlier in this thread that aftermarket synchro parts for the 5MT weren't available. Well PPG have them available and I have included a quote from their website below. Follow the link for more info on whats available for WRXs. Hope this helps those looking to replace synchros.

"At PPG we make the Synchromesh rings and hubs considerably stronger than factory components and incorporate our high quality materials and heat treating processes into the finished product ensuring durability you can rely upon for years to come."

The point was made earlier in this thread that aftermarket synchro parts for the 5MT weren't available. Well PPG have them available and I have included a quote from their website below. Follow the link for more info on whats available for WRXs. Hope this helps those looking to replace synchros.

"At PPG we make the Synchromesh rings and hubs considerably stronger than factory components and incorporate our high quality materials and heat treating processes into the finished product ensuring durability you can rely upon for years to come."

Keep in mind that PPG stuff is completely the BEST out there...and for them to BE the best...they need make EVERYTHING for it...so that should not be a suprise to anyone that they make syncros as well.

Personally, I've never had a problem with a SUBARU syncro unless it has been abused or misused for long periods of time.

ok so i experienced my 2nd shearing of 1st and 2nd......im proud to say actually lol. actually the 1st time it broke they (warranty company) replaced it with a factory salvaged unit. this time im getting a "new" tranny put in my 02 bugeye. my question is have they since fixed the ever so popular gearbox problem. just curious as to how accurate the suby service center was with me. he already tried to tell me that the sti ra gearbox would not fit in my car so i was already skeptical by that remark. just curious considering the warranty is buying this 4000 dollar tranny brand new not remanufactureed and i dont want to have the same problems that i have had in the past. all im running is downpipe, header and uppipe, catback, cobb intake, gfb hybrid bov, fixing to go with the 3/16 mod from boostkits when it gets out of the shop, and a dc sports short throw. aggresive driver but no clutch dumps, synchro grinds, more or less full throttle with smooth shifts. dont think im overpowering it by no means. lemme know what u think. thanks !!!!!blubaru nation!!!!!

I do have a question that many of you may be interested in. Calculating from my elementary math skills, our cars have an approximate 29% power loss. That is a big number in my books and I'd love to lower that number.

Carbon fiber driveshaft does help reduce a little of that power loss due to its light rotational mass and diameter. However, the majority of the drivetrain loss is in the transmission and its gears. Then there's the lightweight clutch and flywheel. But that's common knowledge on NASIOC.

What I'm interested in is reduction of lower loss in the transmission unit itself. As far as I know, our gears are made of steel for cost, strength, and shock absorption reasons. Have there been any lightweight gears made from different materials (titanium comes to mind) that would significantly reduce this transmission loss?

A quick search on Google and Eng-tips.com came up with no available product (we're not discussion about Subaru's only, but motorsports in general for any make). Eng-tips hinted that Titanium was tried before yet failed miserable approximately 5-10 years ago due to some problems they could not overcome (the engineering jargon was hieroglyphics to me). The majority of the issue I believe with the titanium gears they tried was its inability to absorb shock due to too much deflection.

Are there any engineers that would be interested in this topic and research along with me?

Ti is too weak for an enviorment such as a transmission or engine. Ti is not god in high temp situations either. Over a short amount of time (compared to how long the stock parts are designed to last) the Ti parts will need to be 'refreshed' back to specs.

Basically...the peices in the 6MT and what PPG have are the best possible.

Ti is too weak for an enviorment such as a transmission or engine. Ti is not god in high temp situations either. Over a short amount of time (compared to how long the stock parts are designed to last) the Ti parts will need to be 'refreshed' back to specs.

Basically...the peices in the 6MT and what PPG have are the best possible.

Like I said, I'm not looking at any drop-in solutions. I'm trying to see if there are possibilities of different materials for gears in transmissions to reduce rotational mass and power loss. This is for ANY car, not just Subarus. Then maybe someone can custom make something that would be beneficial for the entire modification community.

A large portion of the extra power loss is due to the twice the amount of ring/pinions, differential bearings, wheel bearings, axles, and cv joints that it has to travel through before it hits all four wheels. I don't think the transmission design is the main power loss culprit here.

A large portion of the extra power loss is due to the twice the amount of ring/pinions, differential bearings, wheel bearings, axles, and cv joints that it has to travel through before it hits all four wheels. I don't think the transmission design is the main power loss culprit here.

Very true. Then it would be a great idea if companies can start designing lightweight axles and joints. =)

Cooling the oil is good. Especially if you can set up a way to redistribute the oil back over at least the first 2 or 3 gears, instead of relying on the "splash" lubrication design that it has.

However, an oil cooler will basically just help to keep the oil from breaking down sooner. In my opinion, gear failures in the transmissions are mainly caused by shockload and, as a result, deflection of the mainshaft (input shaft). Cooler gear oil won't keep that shaft from flexing.

Hey Guys, Im looking at two different gearing options. The STI RA and the STI SE gear sets. Which would you reccomend for me to upgrade my 2007 wrx 5mt with and which will behave better daily driving/ spirited driving. I wont be exceeding 350 hp in any form. Probably around 300.

And does anyone know if the OBX racing helical front LSD that fits the 02- 05 wrx will function correctly in my 07 wrx case?

Hey Guys, Im looking at two different gearing options. The STI RA and the STI SE gear sets. Which would you reccomend for me to upgrade my 2007 wrx 5mt with and which will behave better daily driving/ spirited driving. I wont be exceeding 350 hp in any form. Probably around 300.

And does anyone know if the OBX racing helical front LSD that fits the 02- 05 wrx will function correctly in my 07 wrx case?

Before you buy any of these, do some research on the Legacy GT gears that come standard on Legacy GT's.

In fact, since you have a push-style clutch, I'm pretty sure all you need is a WRX specific front diff a speedo gear to install a Legacy GT transmission in your car.

The OBX one you mentioned would fit the bill for either a re-build or the Legacy GT transmission.

This is driving crazy. IS THE LEGACY GT TRANSMISSION AN UPGRADE FOR THE 06-07 WRX? yes or no. Andretech says no, so which one is it? I ask this question like six months ago, I also spend sometime on the legacy gt forums and I found that no one has broken their tranny but most of them don't mod their cars either .

Yeah, could someone confirm/deny it? I read that LGT 5MT gears are same as JDM STI non-RA gears. So they should be stronger than WRX gears. Also there are very few reports of LGT transmission failures even on high-powered LGTs, which with 2.5L push way more torque than 2.0L WRX...

Are the LGT gears an upgrade for the 06-07 WRX owners? No. I mean, gear ratio is different, and the numerically higher ratios will be marginally stronger, but it would be unnoticeable. If you had the power to break an 06-07 box, you'll break an LGT box.

As for that material, design, lightweight comment before.

1) Gears need to be steel. Steel is typically heavy. The majority of steels have densities in the same .28x lb/cubic inch range. Something like aluminum lacks the mechanical properties that would allow them to be subjected to the stress associated with gear-train drive systems. If you think that "steel" is too limited, remember that there are HUNDREDS of different types of steel, each with unique mechanical properties. Add to that the, literally, infinite modes of heat treatment and post processing to achieve specific mechanical properties, and you'll find that "steel isn't steel isn't steel".

2) The astronomical cost of exotic materials, like magnesium or berylium, would... have astronomical costs. They COULD be designed to be much stronger and much lighter, but they'd also cost about as much as the purchase price of a small secluded island off the coast of South Africa.

3) You have physical dimension requirements. Gear ratios are dictated by tooth count. To have the number of teeth required for the ratios you want, you need to have enough of a diameter gear to achieve it. To do THAT, you have to use a specific amount of material. You could do things like scallop the sides of the gears, or make the gears narrower to reduce weight and increase efficiency, but you sacrifice strength to do so. Plus, our gears are loaded in both directions (depending on acceleration/deceleration), so any face modification would have to account for that.

4) In terms of efficiency, there is a notable increase in efficiency when switching from helical gears to straight cut gears. Less energy is wasted trying to push the gears longitudinally apart (thrust load, trying to walk one shaft towards the engine, and the other out the rear of the case) and the savings is transferred to the shaft and out to the wheels. If efficiency is your bag, opt for straight cuts over helical. You'll still lose some energy in other ways that you weren't losing with helical (some energy transferred into sound, for example), but the net energy lost will be less with straight cut gears than helical gears.

5) The AWD "stuff" does account for a decrease in performance. Still, you'd find not much more than a 2%-5% increase in economy if you DID convert to RWD (bypassing the front diff all together). Any gear change is going to impart some loss of efficiency. That's the nature of gear reduction/modification. You lose energy during the process.

6) If you want to idealize efficiency, get 4 rotary engines, mount one at each wheel, and direct drive them. Size the tire right, and you should be able to have a reasonably decent high-speed performer with enough boost. Actually getting off the line, however, would be a feat of black magic. Ever tried getting your Subaru rolling in 4th gear? Give it a shot before actually thinking this kind of thing is a good idea. The alternative to this is to use 4 electric motors at each wheel, direct drive them, and have a turbo diesel 4-cylinder bolted to a generator.

Just my take on the lightweight, efficiency stand. Designing a system from the ground up would remove many of these concerns, but that's still impractical when it comes to cost. What can realistically be done, is modify the current offerings (new gears in a stock case), and that is limited as above.

The root cause of gear tooth shear as the OP pointed out was shaft flex, mainly on the input. All of the talk in this thread has been about gears. Why?

If the root cause of the failure is the input shaft, what options do we have to eliminate input shaft flex? Can we support the shaft at another location (I'm guess not)? Can we make a shaft out of stronger material? Heat treat and cyro treat the stock shaft?

Anyone know what the material (obviously steel, more specifically) is on the stock input shaft and the treatments it received?

Well I know this doesn't have much to do with the thread, but people with transmission questions are usually looking for an upgrade.

It was said earlier that ppg are the best gears you can buy and many people can't afford them, but Albins makes a gearset that is both affordable and reliable(from tests by a few shops). Here is a link to the thread if anyone is interested: Albins Thread

+1 I really like Albins gear sets myself and will choose them over other manufactures. I think most people recommended PPG since there was no other alternative at that time. Albins just started to sell their product to US and what was previously only available to race teams is now being offered to the public.

Well I know this doesn't have much to do with the thread, but people with transmission questions are usually looking for an upgrade.

It was said earlier that ppg are the best gears you can buy and many people can't afford them, but Albins makes a gearset that is both affordable and reliable(from tests by a few shops). Here is a link to the thread if anyone is interested: Albins Thread

Sure, it's news to most of us in the U.S. However, until someone does a fair side-by-side comparison with other solutions such as PPG and MFactory, all the hype isn't that helpful, other than saying there's another product available. All the Albins stuff I've heard/read basically sounds like a polished sales pitch. Almost like someone cut and pasted the words off a brochure.

Also, one of the complaints about PPGs that folks throw out there are the high pricing. Who's to say that Albins won't be more expensive? One thing that I've pointed out in the various 6-speed versus PPG versus MFactory postings is what is the final cost? How much will it set back the person who's car that it's going into? You not only need to factor in the parts, there's install costs, downtime, etc.

Artie from Agile - Have you actually experienced Albins in a Subaru or a different car manufacturer? Just curious.